Wiping cloth for removing microbes

ABSTRACT

A wiping cloth removes microbes and is capable of picking up dirt from the wiped surface of an object and trapping the dirt into the cloth to ensure the retention of the trapped dirt. The wiping cloth is made of a fabric including 50 to 80% by weight of synthetic microfibers with a single fiber fineness of below 1.0 dtex and having a bulk of 2.0 cm 3 /gr or more.

TECHNICAL FIELD

This disclosure relates to a wiping cloth for removing microbes.

BACKGROUND

Wiping cloths are conventionally used for the cleaning of glasses andlenses, and as the electronic information society has rapidly developed,they have become increasingly used to clean screens of electronicdevices, as typified by liquid crystal display screens and, accordingly,required to have high dirt removal performance. The requirement,however, cannot be satisfied by conventional cotton or paper wipingcloths because lint and dust should be avoided in the electronic field.In addition to the electronic information field, wiping cloths have alsobecome increasingly used at home and in hospitals and, consequently,there has been a demand for wiping cloths with a high durability and ahigh antibacterial performance.

As an example of such a wiping cloth, JP 9-19393 A discloses ahigh-density woven fabric made from a composite yarn consisting ofsynthetic microfibers and synthetic high denier fibers, which wipingcloth exhibits excellent performance in wiping away oil stains and dirtfrom glass lenses. However, the mere use of a composite yarn isinsufficient to completely wipe away the oil stains and dust from thesurface of the lenses, and spreads the oil stains and dust, resulting ina leftover residue. A wet cloth containing a cleaning liquid is alsosometimes used for wiping an object. After wiping, however, thechemicals contained in the wet cloth may be left as a residue on thesurface of the object, and dirt cannot be completely removed.

In addition, disinfectant liquid cleaners, and the like containingalcohols and chemicals cannot be used for particular medical devices inthe medical sites because the alcohols and the chemicals willdeteriorate the plastic cases, touch panels, operation screens, and thelike of the devices.

It could therefore be helpful to provide a wiping cloth for removingmicrobes, which is capable of picking up dirt from the wiped surface ofan object and trapping the dirt in the cloth to ensure retention of thetrapped dirt.

SUMMARY

We thus provide:

(1) A wiping cloth for removing microbes, the wiping cloth made of afabric comprising 50 to 80% by weight of synthetic microfibers with asingle fiber fineness of below 1.0 dtex and having a bulk of 2.0 cm³/gor more.(2) The wiping cloth for removing microbes according to the above (1),wherein the single fiber fineness of the synthetic microfibers is 0.1dtex or less.(3) The wiping cloth for removing microbes according to the above (1) or(2), wherein the fabric comprises high shrinkage fibers.(4) The wiping cloth for removing microbes according to any of the above(1) to (3), wherein at least some of the fibers in the fabric arefalse-twisted.(5) The wiping cloth for removing microbes according to any of the above(1) to (4), wherein the fabric is treated by water jet punching.(6) The wiping cloth for removing microbes according to any of the above(1) and (3) to (5), made of a fabric made from a composite yarnconsisting of 50 to 80% by weight of synthetic microfibers with a singlefiber fineness of below 1.0 dtex and 50 to 20% by weight of synthetichigh denier fibers with a single fiber fineness of 1 dtex or more.(7) The wiping cloth for removing microbes according to the above (6),wherein the single fiber fineness of the synthetic microfibers is 0.1dtex or less.(8) The wiping cloth for removing microbes according to any of the above(1) to (7), which has an ATP level of 100 RLU or less, the ATP levelserving as an indicator of the amount of dirt in accordance with theabundance of organisms.(9) A method of removing microbes, the method comprising wiping with thewiping cloth for removing microbes according to any of the above (1) to(8) that is damped with water.

The wiping cloth comprises 50 to 80% by weight of synthetic microfiberswith a single fiber fineness of 0.1 dtex or less, and the syntheticmicrofibers are capable of picking up dirt from the wiped surface of anobject and trapping the dirt. The wiping cloth also has a fabricstructure having a bulk of 2.0 cm³/g or more and a large number ofspaces communicating with each other, and the structure ensures that thedirt is trapped in the fabric and retention of the trapped dirt and doesnot allow the dirt to disperse out of the fabric.

DETAILED DESCRIPTION

Examples of our wiping cloth will be described below.

(1) Synthetic Microfibers and Bulk Volume

The wiping cloth is made of a fabric comprising 50 to 80% by weight ofsynthetic microfibers with a single fiber fineness of below 1.0 dtex andhaving a bulk of 2.0 cm³/g or more. The single fiber fineness of thesynthetic microfibers is below 1.0 dtex, preferably 0.1 dtex or less,more preferably 0.01 to 0.08 dtex, further more preferably 0.05 to 0.06dtex. The amount of the synthetic microfibers of below 1.0 dtexcontained in the fabric is preferably 50 to 80% by weight, morepreferably 60 to 70% by weight, to achieve adequate bulkiness, texture,and wiping performance of the fabric. The bulk of the fabric ispreferably 2.0 cm³/g or more to efficiently trap dirt into the fabric.The bulk of the fabric is preferably 10 cm³/g or less to ensureretention of the trapped dirt in the fabric.

(2) High Shrinkage Fibers

The fabric preferably comprises high shrinkage fibers with a singlefiber fineness of 1 dtex or more. The high shrinkage fibers of 1 dtex ormore imparts bulk to the fabric. The fineness of the high shrinkagefibers is more preferably 2 to 4 dtex. The shrinkage (%) of the highshrinkage fibers of 1 dtex or more is not particularly limited as longas the shrinkage is high. Preferably, the shrinkage under heat of thehigh shrinkage fibers is higher than that of the synthetic microfibers.For example, when the shrinkage in boiling water of the syntheticmicrofibers is about 4 to 8%, the shrinkage in boiling water of the highshrinkage fibers of 1 dtex or more is preferably about 10 to 25%. Thatis, the shrinkage in boiling water of the high shrinkage fibers of 1dtex or more is preferably higher than that of the syntheticmicrofibers. When the shrinkages of the two types of fibers are asdescribed above, stronger shrinkage occurs under heat treatment in thehigh shrinkage fibers of 1 dtex or more than in the syntheticmicrofibers and, as a result of this shrinkage behavior, the filamentorientation in the synthetic microfibers is disturbed and the bulk ofthe surface of the fabric is increased.

(3) False Twisting

The synthetic microfibers are preferably crimped by false twisting. Thecrimping by false twisting disturbs the filament orientation andenhances the wiping performance and dust-trapping performance of thesurface of the fabric. False twisting can be performed by usual woollytexturing.

(4) Knitted and Woven Fabrics

The wiping cloth may be a woven fabric, a knitted fabric, or a nonwovenfabric, but is not limited thereto. The wiping cloth may be a compositefabric of a woven or knitted fabric and a nonwoven fabric. Preferred isa knitted fabric, because by disturbing the orientation of theconstituent filaments, a knitted fabric is made into a wiping cloth thatcan be used without any limitation of the wiping direction. Suchdisturbance of the filament orientation is achieved by, for example,water jet punching, and as a result of this treatment, the syntheticmicrofibers on the surface are partially entangled with the synthetichigh denier fibers and the directions of the loops are randomized.

(5) Water Jet Punching

The fabric is preferably subjected to water jet punching to createspaces in the fabric. The water jet punching is performed by ejectingfilter-purified water from small nozzles at a given pressure to thesurface of the fabric. The water pressure is preferably 30 to 120kgf/cm², more preferably 50 to 80 kgf/cm². Water jet punching at a waterpressure of below 30 kgf/cm² is not significantly effective, resultingin lack of shape stability and insufficient entanglement of the fibers.In contrast, water jet punching at a water pressure of above 120 kgf/cm²may cause breakage of the filaments in the synthetic microfibers, whichbreakage may cause lint.

(6) Synthetic Microfibers and Synthetic High Denier Fibers

To achieve adequate bulk and an adequate wiping performance of thefabric, the fabric is preferably made from a composite yarn comprisingsynthetic microfibers with a single fiber fineness of 0.1 dtex or lesspreferably in an amount of 50 to 80% by weight, more preferably in anamount of 60 to 70% by weight, and synthetic high denier fibers with asingle fiber fineness of 1 dtex or more in an amount equal to theremaining percentage. The single fiber fineness of the synthetic highdenier fibers is 1 dtex or more, preferably 2 to 4 dtex. The fabricshould not comprise synthetic high denier fibers with single fiberfineness of above 4 dtex, which fibers may deteriorate the texture andwiping performance of the fabric. The above-described synthetic highdenier fibers with a single fiber fineness of 1 dtex or more serves ashigh shrinkage fibers and are thus preferably not subjected to falsetwisting.

(7) ATP Levels

The water jet-punched fabric is dried at 100° C. or higher forevaporation of the moisture and hydrophilic components. The fabric isthen cut into an appropriate size as a product, washed with ultrapurewater (or a liquid having an equivalent function), dried, and packagedin a clean room to produce a clean product (a wiping cloth for removingmicrobes). The term “clean product” herein refers to a product on thesurface of which the total amount of ATP (adenosine triphosphate) andAMP (adenosine monophosphate) present is at a certain level or lower.The ATP levels will be further described below.

ATP is an essential energy substance for every organism. ATP iscontained in dirt derived from microorganisms or organisms and, hence,the measurement of the amounts of ATP and AMP, a product of ATPdecomposition, contained in the microbe-removing wiping clothobjectively confirms the contamination by microbes. The measurement isperformed using, for example, a luminescence reagent containing fireflyluciferase, luciferin, and pyruvate phosphate dikinase (PPDK). Fireflyluciferase produces light in the presence of ATP and luciferin. Thisreaction also produces AMP. The AMP is converted into ATP by PPDK andagain subjected to the reaction with the luminescent reagent. In thismanner, the intensity of the light corresponding to the total amount ofATP is obtained. The intensity of the light is then measured with aparticular measuring device to determine the degree of dirt.

(8) Method of Determining Degree of Dirt

An exemplary method of determining the degree of dirt will bespecifically described below.

Object Subjected to Measurement

The object to be subjected to the measurement is a SUS304 flat board.The surface of the board is cleaned by wiping with purified water beforethe measurement.

Spraying of Dirt Substance

On the surface of the board, a 5% by weight aqueous solution of yeastextract is sprayed at 0.1 g/0.05 m² with an atomizer.

Wiping Off of Dirt Substance

A cotton swab is wetted with 0.05 g of purified water, and the surfaceof the board on which the dirt substance has been sprayed is wiped withthe cotton swab under a load of 1.2 kg by sliding the cotton swab backand forth across a distance of 40 cm ten times so that the aqueoussolution of yeast extract is removed with the cotton swab.

Measurement of Intensity of Light

The cotton swab used to wiped off the aqueous solution of yeast extractis immersed in an extraction reagent (containing a surfactant(benzalkonium chloride)) to extract ATP. The extracted ATP is reactedwith a luminescent reagent containing firefly luciferase, luciferin andPPDK to produce light. The intensity of the light is measured with aluminescence meter (for example, “Lumitester PD-20” (trade name)produced by Kikkoman Biochemifa Company). The value of the ATP level ofthe dirt substance when measured with the luminescence meter isexpressed as a relative light unit (RLU) and will be within the range of10000±500 (RLU).

Clean Product

In the field of medical devices, which is considered to have thestrictest demands for cleanliness, the relative light unit of the amountof ATP on an endoscope is often required to be 100 RLU or less.

(9) Applications of Wiping Cloth for Removing Microbes

The wiping cloth is capable of picking up and trapping dirt thereinto,as if it scrapes the dirt, and does not leave a streaky residue. Due tothese advantages, the wiping cloth is applicable to various devices ofwhich the surfaces require high cleanliness. For such applications, thewiping cloth is wetted with water to exhibit an improved wipingperformance. The wiping cloth does not require chemicals such asalcohols and disinfectant liquid cleaners and, hence, does notdeteriorate the wiped surface of an object and does not affect theappearance of the surfaces of devices. The wiping cloth is, therefore,applicable to maintenance of various types of medical devices thatrequire extreme cleanliness (for example, infant incubators, PET,PET/CT, and the like).

(10) Thickness of Wiping Cloth for Removing Microbes

The thickness of the wiping cloth for removing microbes has a largeinfluence on the dirt-wiping performance and the handling property, andis thus preferably 100 μm to 2 mm. The wiping cloth with a thickness of500 μm to 1 mm exhibits more preferred wiping performance and handlingproperty. However, the wiping cloth with a thickness of below 100 μmcannot sufficiently pick up dirt and thus is not preferred. The wipingcloth with a thickness of above 2 mm exhibits poor handling property andrequires more production cost and thus is also not preferred.

EXAMPLES

Our wiping cloths will be specifically described with reference toExamples, but are not limited to thereto. Various alterations andmodifications are possible without departing from the technical scope ofthis disclosure.

Example 1

The synthetic microfibers used were “UTS” of 66 dtex and 9 filamentsproduced by Toray Industries, Inc. (an islands-in-the-sea type compositepolyester ultrafine micro yarn splittable with a solvent (alkaline hotwater-soluble polyester fibers composed of polyethylene terephthalate asthe island component and a copolymer of polyester with terephthalic acidand 5-sodium sulfoisophthalic acid (acid units) as the sea component,with the ratio of the island and sea components of 20/80, and ashrinkage in boiling water of 9%)). The synthetic high denier fibersused were a polyester yarn of 33 dtex and 6 filaments (produced by TorayIndustries, Inc., a high shrinkage yarn with a shrinkage in boilingwater of 21%). The synthetic microfibers were false-twisted, arranged inparallel with the synthetic high denier fibers, and air-entangled toproduce a composite yarn. The yarn was interlock knitted with a circularknitting machine (32 G, 97 cm) to produce a greige fabric. The greigefabric was heat treated at 130° C. for 20 minutes and then treated at80° C. for 30 minutes in the presence of 1% sodium hydroxide tocompletely remove the sea component. The fineness of the microfibersafter removal of the sea component was 0.08 dtex. The fabric was thenwater jet-punched with water ejected to the surface at a pressure of 100kg/cm². The fabric was heat set at 135° C. so that the wale and coursecounts were 60/2.54 cm. The fabric was washed with ultrapure water anddried at 80° C. The obtained knitted fabric contained 65% by weight ofthe synthetic microfibers and was highly dense with the number of theconstituent filaments, most of which were the synthetic microfibers,being about 35000/2.54 cm both in the wale and course directions. Thesingle fiber fineness of the synthetic microfibers in the knitted fabricwas 0.08 dtex, and the single fiber fineness of the synthetic highdenier fibers in the knitted fabric was 2.4 dtex.

The bulk of the high-density knitted fabric was 2.6 cm³/g, and thethickness was 0.52 mm.

The bulk and thickness of the high-density knitted fabrics herein weredetermined as follows, with reference to JIS L1018 (Test methods forknitted fabrics).

Measurement of Thickness

A square sample of 20 cm in width and length was cut out from a knittedfabric and the thickness was measured with a thickness gauge under apredetermined pressure applied with a presser foot. The diameter of thepresser foot was 10 cm². The pressure was 7 gf/cm². Ten seconds afterapplying the pressure, the dial gauge (peacock dial gauge) was read todetermine the thickness t (mm) of the knitted fabric.

Measurement of Bulk

The weight (g/m²) of the square sample of 20 cm in width and length wasmeasured, and the bulk (cm³/g) was calculated from the above thickness t(mm) and the weight W (g/m²) based on the following formula:

Bulk (cm³/g)=(t/W)×1000.

Measurement of ATP Levels (1) Before the First Wiping

In the same manner as described above, on the surface of a SUS304 flatboard, a 5% by weight aqueous solution of yeast extract was sprayed, theaqueous solution of yeast extract was wiped off with a cotton swab, andthe ATP level of the cotton swab was measured with a luminescence meteras described above to determine the ATP level before the first wiping.

(2) After the First Wiping

After the above measurement of the ATP level on the surface of theSUS304 board as described above, the following procedures wereperformed. The high-density knitted fabric (the wiping cloth forremoving microbes) produced as described above was wrapped around arectangular pad of 6 cm×4 cm to produce a testing wiping cloth. Thetesting wiping cloth with a 1.2-kg metal weight on it was placed on thesurface of the SUS304 board on which the 5% by weight aqueous solutionof yeast extract was sprayed (a different part of the surface of theSUS304 board from the part from which the solution was wiped off withthe cotton swab described above), and the wiping cloth was then slid fora distance of 10 cm to wipe off the aqueous solution of yeast extract.The same part of the surface of the SUS304 board from which the aqueoussolution of yeast extract was wiped off with the testing wiping clothwas wiped with a cotton swab under a load of 1.2 kg by sliding thecotton swab back and forth across a distance of 40 cm ten times. The ATPlevel of the cotton swab was measured with a luminescence meter asdescribed above to determine the ATP level after the first wiping.

(3) Testing Wiping Cloth (Wiping Cloth for Removing Microbes WrappedAround a Rectangular Pad of 6 cm×4 cm)

The surface of the testing wiping cloth before used for wiping thesurface of the SUS304 board was wiped with a cotton swab under a load of1.2 kg by sliding the cotton swab back and forth across a distance of 40cm ten times. The ATP level of the cotton swab was measured with aluminescence meter as described above to determine the ATP level of thetesting wiping cloth before wiping. The testing wiping cloth was thenused to wipe the surface of the SUS304 board on which the 5% by weightaqueous solution of yeast extract was sprayed as described above, andthe ATP level of the testing wiping cloth was measured in the samemanner as described above to determine the ATP level of the testingwiping cloth after the first wiping.

In the same manner as described above, the ATP levels on the surface ofthe SUS304 board were measured with a luminescence meter before andafter the second to the fifth wiping, and the ATP levels of the testingwiping cloth were measured with a luminescence meter after the second tothe fifth wiping.

Table 1 shows the relative light units (RLUs) indicating the ATP levelswhen dry wiping was performed with the testing wiping cloth in a mannerthat the direction of wiping coincided with the wale direction. Table 2shows the RLUs indicating the ATP levels when dry wiping was performedwith the testing wiping cloth in a manner that the direction of wipingwas perpendicular to the wale direction. Table 3 shows the RLUsindicating the ATP levels when the testing wiping cloth was damped withpurified water at 0.1 g/24 cm³ and then damp wiping was performed withthe wiping cloth in a manner that the direction of wiping coincided withthe wale direction. Table 4 shows the RLUs indicating the ATP levelswhen the testing wiping cloth was damped with purified water at 0.1 g/24cm³ and then damp wiping was performed with the wiping cloth in a mannerthat the direction of wiping was perpendicular to the wale direction. InTables 1 to 12, the term “degree of cleaning” means the remainder aftersubtraction of the ATP level after wiping from the ATP level beforewiping, and the term “percentage degree of cleaning” means the ratiocalculated by subtracting the ATP level after wiping from the ATP levelbefore wiping and dividing the remainder by the ATP level before wiping.

TABLE 1 SUS304 board surface Percentage Testing wiping cloth BeforeAfter Degree of degree of ATP level wiping wiping cleaning cleaning (%)before wiping: 35 1st 10034 782 9252 92.2 After wiping: 49 2nd 10493 6129881 94.2 After wiping: 100 3rd 9681 736 8945 92.4 After wiping: 83 4th10367 458 9909 95.6 After wiping: 128 5th 9725 455 9270 95.3 Afterwiping: 138

TABLE 2 SUS304 board surface Percentage Testing wiping cloth BeforeAfter Degree of degree of ATP level wiping wiping cleaning cleaning (%)before wiping: 28 1st 10156 539 9617 94.7 After wiping: 112 2nd 10391562 9829 94.6 After wiping: 149 3rd 10417 438 9979 95.8 After wiping: 784th 10021 763 9258 92.4 After wiping: 109 5th 9968 657 9311 93.4 Afterwiping: 152

TABLE 3 SUS304 board surface Percentage Testing wiping cloth BeforeAfter Degree of degree of ATP level wiping wiping cleaning cleaning (%)before wiping: 40 1st 10147 82 10065 99.2 After wiping: 75 2nd 9516 989418 99.0 After wiping: 28 3rd 9837 77 9760 99.2 After wiping: 41 4th10439 58 10381 99.4 After wiping: 60 5th 9642 38 9604 99.6 After wiping:59

TABLE 4 SUS304 board surface Percentage Testing wiping cloth BeforeAfter Degree of degree of ATP level wiping wiping cleaning cleaning (%)before wiping: 35 1st 10492 64 10428 99.4 After wiping: 40 2nd 10382 7210310 99.3 After wiping: 101 3rd 9688 85 9603 99.1 After wiping: 39 4th10256 43 10213 99.6 After wiping: 78 5th 10437 29 10408 99.7 Afterwiping: 62

As is apparent from Tables 1 to 4, the water jet-punched wiping clothshowed no difference in the ATP levels on the surface of the SUS304board between the cases of wiping in the wale direction and wipingperpendicular to the wale direction both in the damp wiping and the drywiping (comparison of Tables 1 and 2, and comparison of Tables 3 and 4).The ATP levels on the surface of the SUS304 board were reduced to agreater extent in the damp wiping (Tables 3 and 4) than in the drywiping (Tables 1 and 2). The increase in the ATP levels on the testingwiping cloth was lower in the damp wiping than in the dry wiping, evenwhen the wiping was repeated.

Example 2

The synthetic microfibers used were “PICEME” of 56 dtex and 18 filamentsproduced by Toray Industries, Inc. (a splitting type yarn composed of apolyamide star-shaped core being surrounded by triangular polyesterfibers between the branches of the star, with a shrinkage in boilingwater of 12%). The synthetic high denier fibers used were a polyesteryarn of 33 dtex and 6 filaments (produced by Toray Industries, Inc., ahigh shrinkage yarn with a shrinkage in boiling water of 21%). Thesynthetic microfibers were false-twisted, arranged in parallel with thesynthetic high denier fibers, and air-entangled to produce a compositeyarn. The yarn was interlock knitted with a circular knitting machine(32 G, 96.5 cm) to produce a greige fabric. The greige fabric was heattreated at 80° C. for 60 minutes in the presence of 2% NaOH in a jetdyeing machine to split the fibers. Splitting the synthetic microfibersresulted in polyester yarns of 0.27 dtex and nylon yarns of 0.93 dtex.The fineness of the synthetic high denier fibers was 30 dtex (6filaments). The obtained fabric was dried at 120° C. for 3 minutes, andfinished by heat setting at 160° C. for 30 seconds to produce a finishedknitted fabric with 151 wales per 2.54 cm and 190 courses per 2.54 cm.The knitted fabric contained 63.5% by weight of the syntheticmicrofibers. The bulk of the high-density knitted fabric was 2.6 cm³/g,and the thickness was 0.52 mm.

In the same manner as described above, the ATP levels on the surface ofthe SUS304 board were measured with a luminescence meter before andafter the first to the fifth wiping, and the ATP levels of the testingwiping cloth were measured with a luminescence meter before wiping andafter the first to the fifth wiping.

Table 5 shows the relative light units (RLUs) indicating the ATP levelswhen dry wiping was performed with the testing wiping cloth in a mannerthat the direction of wiping coincided with the wale direction. Table 6shows the RLUs indicating the ATP levels when dry wiping was performedwith the testing wiping cloth in a manner that the direction of wipingwas perpendicular to the wale direction. Table 7 shows the RLUsindicating the ATP levels when the testing wiping cloth was damped withpurified water at 0.1 g/24 cm³ and then damp wiping was performed withthe wiping cloth in a manner that the direction of wiping coincided withthe wale direction. Table 8 shows the RLUs indicating the ATP levelswhen the testing wiping cloth was damped with purified water at 0.1 g/24cm³ and then damp wiping was performed with the wiping cloth in a mannerthat the direction of wiping was perpendicular to the wale direction.

TABLE 5 SUS304 board surface Percentage Testing wiping cloth BeforeAfter Degree of degree of ATP level wiping wiping cleaning cleaning (%)before wiping: 38 1st 10162 754 9408 92.6 After wiping: 106 2nd 103371132 9205 89.0 After wiping: 92 3rd 10006 987 9039 90.3 After wiping: 694th 9731 815 8916 91.6 After wiping: 97 5th 10418 1023 9395 90.2 Afterwiping: 134

TABLE 6 SUS304 board surface Percentage Testing wiping cloth BeforeAfter Degree of degree of ATP level wiping wiping cleaning cleaning (%)before wiping: 42 1st 9570 529 9041 94.5 After wiping: 142 2nd 10472 46710005 95.5 After wiping: 84 3rd 10221 352 9869 96.6 After wiping: 79 4th9856 618 9238 93.7 After wiping: 104 5th 9735 438 9297 95.5 Afterwiping: 116

TABLE 7 SUS304 board surface Percentage Testing wiping cloth BeforeAfter Degree of degree of ATP level wiping wiping cleaning cleaning (%)before wiping: 22 1st 9501 135 9366 98.6 After wiping: 36 2nd 9516 1499367 98.4 After wiping: 48 3rd 9837 120 9717 98.8 After wiping: 61 4th10439 125 10314 98.8 After wiping: 59 5th 9642 172 9470 98.2 Afterwiping: 77

TABLE 8 SUS304 board surface Percentage Testing wiping cloth BeforeAfter Degree of degree of ATP level wiping wiping cleaning cleaning (%)before wiping: 31 1st 9739 108 9631 98.9 After wiping: 98 2nd 10452 8910363 99.1 After wiping: 47 3rd 10337 112 10225 98.9 After wiping: 584th 10272 72 10200 99.3 After wiping: 71 5th 10319 58 10261 99.4 Afterwiping: 63

As is apparent from the results for the non-water jet-punched wipingcloth in Tables 5 to 8, wiping perpendicular to the wale directionresulted in larger decreases in the ATP levels on the surface of theSUS304 board than wiping in the wale direction (comparison of Tables 5and 6, and comparison of Tables 7 and 8). The ATP levels on the surfaceof the SUS304 board were reduced to a greater extent in the damp wiping(Tables 7 and 8) than in the dry wiping (Tables 5 and 6). The increasein the ATP levels on the testing wiping cloth was lower in the dampwiping than in the dry wiping, even when the wiping was repeated.

Comparative Example 1

The synthetic fibers used were a polyester false-twisted yarn of 82.5dtex and 72 filaments. The yarn was interlock knitted with a circularknitting machine (28 G) to produce a greige fabric. The greige fabricwas washed with hot water at 60° C. for 10 minutes in a jet dyeingmachine and then washed with water at room temperature. The greigefabric was scoured with caustic soda and a low foaming scouring agentcontaining a polyoxyalkylether compound as its main component to removethe oil adhering to the greige fabric. The surface of the polyesterfibers was slightly melted to impart a hydrophilic nature to thepolyester fibers. The fabric was then washed twice with hot water at 60°C. for 10 minutes so that the caustic soda was removed as much aspossible. The fabric was dried and heat-set at 160° C. The fabric waswashed with ultrapure water and dried at 80° C. The single fiberfineness of the synthetic fibers in the knitted fabric was 2.1 dtex.

The bulk of the high-density knitted fabric was 5.2 cm³/g, and thethickness was 0.74 mm.

In the same manner as described above, the ATP levels on the surface ofthe SUS304 board were measured with a luminescence meter before andafter the first to the fifth wiping, and the ATP levels of the testingwiping cloth were measured with a luminescence meter before wiping andafter the first to the fifth wiping.

Table 9 shows the relative light units (RLUs) indicating the ATP levelswhen dry wiping was performed with the testing wiping cloth in a mannerthat the direction of wiping coincided with the wale direction. Table 10shows the RLUs indicating the ATP levels when dry wiping was performedwith the testing wiping cloth in a manner that the direction of wipingwas perpendicular to the wale direction. Table 11 shows the RLUsindicating the ATP levels when the testing wiping cloth was damped withpurified water at 0.1 g/24 cm³ and then damp wiping was performed withthe wiping cloth in a manner that the direction of wiping coincided withthe wale direction. Table 12 shows the RLUs indicating the ATP levelswhen the testing wiping cloth was wetted with purified water at 0.1 g/24cm³ and then damp wiping was performed with the wiping cloth in a mannerthat the direction of wiping was perpendicular to the wale direction.

TABLE 9 SUS304 board surface Percentage Testing wiping cloth BeforeAfter Degree of degree of ATP level wiping wiping cleaning cleaning (%)before wiping: 56 1st 10345 4327 6018 58.2 After wiping: 197 2nd 102745187 5087 49.5 After wiping: 731 3rd 10105 8026 2079 20.6 After wiping:804 4th 10378 7237 3141 30.3 After wiping: 1003 5th 10467 5895 4542 43.7After wiping: 977

TABLE 10 SUS304 board surface Percentage Testing wiping cloth BeforeAfter Degree of degree of ATP level wiping wiping cleaning cleaning (%)before wiping: 67 1st 10042 6701 3341 33.3 After wiping: 623 2nd 98984368 5530 55.9 After wiping: 551 3rd 9872 4629 5043 52.1 After wiping:670 4th 10430 6552 3878 37.2 After wiping: 785 5th 10216 8798 1418 13.9After wiping: 843

TABLE 11 SUS304 board surface Percentage Testing wiping cloth BeforeAfter Degree of degree of ATP level wiping wiping cleaning cleaning (%)before wiping: 37 1st 9827 291 9536 97.0 After wiping: 4685 2nd 10318346 9972 96.6 After wiping: 7285 3rd 10492 953 9539 90.9 After wiping:13573 4th 9684 684 9000 92.9 After wiping: 18076 5th 10251 773 9478 92.5After wiping: 24310

TABLE 12 SUS304 board surface Percentage Testing wiping cloth BeforeAfter Degree of degree of ATP level wiping wiping cleaning cleaning (%)before wiping: 44 1st 10356 456 9900 95.6 After wiping: 7561 2nd 10446574 9872 94.5 After wiping: 8956 3rd 10378 721 9657 93.1 After wiping:10072 4th 10210 864 9346 91.5 After wiping: 15737 5th 9619 690 8929 92.8After wiping: 19359

As is apparent from Tables 9 to 12, the ATP levels of the surface of theSUS304 board were reduced to a much greater extent in the damp wiping(Tables 11 and 12) than in the dry wiping (Tables 9 and 10). However,even when the damp wiping was performed, the ATP levels after the wipingwas about 300 RLU or more in Comparative Example 1. Such a wiping clothwith large-diameter fibers as in Comparative Example 1 is not expectedto exert our effect of “trapping dirt in the entanglement of syntheticmicrofibers and synthetic high denier fibers and retaining the dirt inthe fabric”, and has thus poor wiping performance.

The above results revealed that an ATP level of about 100 RLU or less isachieved by damp wiping with a water jet-punched wiping cloth comprisingsynthetic microfibers as its main constituent and having a high bulk, orby damp wiping with a non-water jet-punched wiping cloth comprisingsynthetic microfibers as its main constituents and having a high bulk ina wiping manner that the direction of wiping is perpendicular to thewale direction.

INDUSTRIAL APPLICABILITY

Our wiping cloth is particularly suitable for removing microbes frommedical devices.

1.-9. (canceled)
 10. A wiping cloth for removing microbes, the wiping cloth made of a fabric comprising 50 to 80% by weight of synthetic microfibers with a single fiber fineness of below 1.0 dtex and having a bulk of 2.0 cm³/g or more.
 11. The wiping cloth according to claim 10, wherein the single fiber fineness of the synthetic microfibers is 0.1 dtex or less.
 12. The wiping cloth according to claim 10, wherein the fabric comprises high shrinkage fibers.
 13. The wiping cloth according to claim 10, wherein at least some of the fibers in the fabric are false-twisted.
 14. The wiping cloth according to claim 10, wherein the fabric is treated by water jet punching.
 15. The wiping cloth according to claim 10, made of a fabric made from a composite yarn consisting of 50 to 80% by weight of synthetic microfibers with a single fiber fineness of below 1.0 dtex and 50 to 20% by weight of synthetic high denier fibers with a single fiber fineness of 1 dtex or more.
 16. The wiping cloth according to claim 15, wherein the single fiber fineness of the synthetic microfibers is 0.1 dtex or less.
 17. The wiping cloth according to claim 10, which has an ATP level of 100 RLU or less, the ATP level serving as an indicator of an amount of dirt in accordance with the abundance of organisms.
 18. A method of removing microbes comprising wiping with the wiping cloth according to claim 10 that is wetted with water.
 19. The wiping cloth according to claim 11, wherein the fabric comprises high shrinkage fibers.
 20. The wiping cloth according to claim 11, wherein at least some of the fibers in the fabric are false-twisted.
 21. The wiping cloth according to claim 11, wherein the fabric is treated by water jet punching.
 22. The wiping cloth according to claim 11, which has an ATP level of 100 RLU or less, the ATP level serving as an indicator of an amount of dirt in accordance with the abundance of organisms.
 23. A method of removing microbes comprising wiping with the wiping cloth according to claim 11 that is wetted with water. 